e.g combustion of octane:
Complete: C8H18(aq) + (25/2)O2(g) -> 8CO2(g) + 9H2O(l)
Incomplete (producing carbon monoxide and water): C8H18(aq) + (17/2)O2(g) -> 8CO(g) + 9H2O(l)
Incomplete (producing soot [carbon] and water): C8H18(aq) + (9/2)O2(g) -> 8C(s) + 9H2O(l)